4th Class Science Matter and Materials

                                                                 Matter and Materials

Matter

Anything that occupies space and has mass is called matter. Everything around us is made up of matter. matter is made up of atoms. Water bottle, school bag, rubber, pencil are all made up of matter.

States of Matter

Matter exists in three forms - solid, liquid and gas. Matter can change from one form to another on heating and cooling.

A solid can change into a liquid. This will happen if you heat the solid. The solid will melt into a liquid. This process is called melting. If you continue to heat the liquid will change into a gas. This is called evaporation. If you fill water in an ice tray and keep it in the freezer, you will see that after some time the liquid water has turned into ice. We say that the water has frozen and the process is called freezing. When a gas cools it change into the liquid state we say that it has condensed. And, the process is called condensation. The formation of rain in the water cycle is a natural example of the change of state of matter.

Changes Around Us

Matter is constantly changing around us. Changes are of two types - physical changes and chemical changes. In physical change, no new substance is formed. Breaking or glass, melting of ice into water are some, examples of physical change. When ice melts the solid water turned to liquid water. It doesn't turn into food or cold drink or anything new. It remains water. Physical changes can be reversed. In a chemical change, new substance is formed. Changing of milk into curd is an example of chemical change. Similarly burning of paper, making of vegetable dishes from raw vegetables, bursting of crackers are some other examples of chemical changes. Unlike physical changes, chemical changes cannot be reversed.

Rocks

Our earth is made up of rocks. Rocks are hard stones.

Pebbles are small pieces of rock.

Rocks are useful to us in many ways. Rocks such as marble, granite and sandstone are used in making buildings.

World's seventh wonder Taj Mahal is made up of white marble.

Soil Formation

• Soil formation starts when rocks break down into smaller pieces due to wind, rain and the sun's heat. These smaller pieces mix with dead and decaying animals and plants to form soil.
• It takes thousands of years to form a small amount of soil.
• Different types of soil contain different types of particles. These particles differ in colour and softness.
• Soil contains pebbles, gravel, clay, humus, water and air. The water trapped in soil is called moisture.
• Soil provides a bed for both animal and plant life.
• We get many useful minerals such as diamond, granite, marble, and ruby from
• Remains of living things found deep under layers of rocks are called fossils.

Minerals

Minerals are chemical substances that occurs in nature. They are formed due to natural processes within the earth. They may be simple substances or very complex ones. Rocks are formed of minerals. Examples of non-metallic minerals are limestone, magnesite, mica, etc. There are

Metallic minerals also such as gold, silver, iron, etc.

Our body needs some minerals such as calcium, sodium and iron in very small quantities for healthy growth. The bulk of minerals is used for industrial needs such as manufacturing of building materials, vehicles, for fuels and for making jewellery.